Topband: BC filter

[Rudy Severns]

Not only is it a good idea to use a BC filter to protect the your preamp but
also use it when making antenna measurements.

    I recently put up a two element array on 160.  While checking the SWR
matching adjustment using an MFJ-249 the results were wildly off from
predictions.  A quick check with an RF millivoltmeter showed 60 mV+ of local
broadcast station signal.  The local station is neither very powerful or
very close.  Putting in a BC filter in line with the MFJ calmed it right
down.  I saw the same problem with more advanced instruments like the HP
4815A and the HP 3577A.

    Almost any antenna on 160 will pick up the local stations and so I make
it standard practice now to use the BC filter.

73, Rudy N6LF